Exactly as you just said, "depending on where your ss is at to being with", I'm benefiting from it more or less. Sure I only gain 0,04s with the weapon. The fact is you do not have to look after the adding weapon, but after the final result. And the final result isn't 0,04s of reduction on each spell but 0,25s. It's not because I chose SS on my novus that it's not the same point of view when you add another stat. They all need A LOT OF POINTS to be efficient a minimum.
So, I totally agree with you about the fact you will never wish you would have casted 0.04 seconds sooner, but you could assume you would maybe wish you would have casted 0,25s sooner, and much more as long as you'll stack the stat.
And not to remind you that when you add 44 crit, you only gain 1,46% healing. When you add 44 det, you only gain 1,60% healing and adding 44 SS, you only gain 2,5% spell speed on each cast. (approximatively with ilvl 100 geared, ofc numbers increase with WD, but it seems the more MND you get, the less DET affects your heals).
So I just can answer you "why would you stack 44 DET knowing you only gain less than 2% healing ?" Oh yeah, because HPS or HPM and I'm alright with your choice.
The thing that annoys me is that most ppl just says "you need tooooooo much SS to actually see the effects of it". And I'll just answer : you need as much CRIT or DET to see the effects of it. Maybe these ppl just looked 1 time on the GCD and cast time with few SS and concluded that was an useless stat, but they probably didn't try to stack this stat to see a big difference.
I'm just saying this because I feel like this stat is underestimated compared to the others and ppl who didn't try it may not want to spend time to try it later after hearing by a lot of ppl it's useless...
I won't argue more, but think about the game, and just wonder yourself why is this stat existing then if it's not worth it ? Why one of the fairy of the SCH job has a buff giving an extra +30% Spell Speed / Skill Speed permanently (assuming your SCH is able to use this fairy) ?
(not trying to mean SS is better than the others stats, only meaning it's worth as much as the others)